Exclude .mailmap in Codeowners (#132722)

Co-authored-by: Hugo van Kemenade <[email protected]>

Author: StanFromIreland

.github/CODEOWNERS

@@ -167,6 +167,9 @@ Include/internal/pycore_time.h  @pganssle @abalkin
 **/*imap*                     @python/email-team
 **/*poplib*                   @python/email-team
 
+# Exclude .mailmap from being owned by @python/email-team
+/.mailmap
+
 # Garbage collector
 /Modules/gcmodule.c           @pablogsal
 /Doc/library/gc.rst           @pablogsal